Why Are Tsunamis So Dangerous? Here Are 5+ Reasons Why.

Just because you don’t feel an earthquake doesn’t mean it didn’t happen. Thankfully, most at-risk coastal regions have tsunami sirens, and the internet keeps the world connected with push notifications. But that doesn’t mean it’s a 100% surety that you will get a fair warning.

If you receive a tsunami warning, immediately find higher ground as far inland as possible.

We will go in-depth about tsunamis and explain the reasons why are tsunamis so dangerous.

What is a tsunami?

Earthquakes happen below or near the ocean floor. Sometimes when they do, it causes sizeable and sudden ocean displacement that leads to waves extending as long as 60 miles (100 kilometers).

Wind does not play a factor in tsunamis because they simply move the topmost layers of water.

A tsunami consists of columns of water that form from the ocean floor to the surface. And while an earthquake is a primary cause, it isn’t the only one.

5 Reasons Why Tsunamis are Dangerous

Don’t let the size of a tsunami fool you, either. Even the baby ones can cause damage to people and property. 

Extreme Flooding

Flooding is the most dangerous part of most weather and naturally occurring events. It’s the rushing water inland that knocks people off of their feet and buildings off of their foundations.

A tsunami can last hours, meaning the flooding will remain dangerous for hours after that. 

Wave Impacts

The massive wall of water is what comes to people’s minds when you talk about tsunamis. But it’s what it brings with it that is the most dangerous.

It’s the wave that knocks you down, but it’s the flooding that carries you away.

4 Warnings Before the Wave

Ideally, there are four levels of tsunami alerts. Whether it’s the first or the last, all warnings should be taken seriously. People should avoid standing around and filming a tsunami wave; death isn’t worth the clout.

  • Tsunami warning. It is the most critical alert and means that there has been a tsunami sighting near you. Go inland and take the higher ground.
  • Advisory. You are being advised that there are tsunami waves near you or are causing dangerous conditions.
  • Watch. Even a tsunami watch is nothing to play with. It means that one may impact your area in the near future.
  • Information statement. This statement is the first sign of trouble. It means that the conditions are tsunami-friendly.


A tsunami causes insta-erosion the moment it impacts the shore. Rapid erosion and deposition of sediment can dramatically alter an entire coastline.

After the wave impact, the threat of erosion remains. It displaces vegetation and leaves ocean debris inland, which will further the erosion process, and makes mudslides an ongoing threat.

Strong Currents

Strong currents can happen miles and miles from the actual tsunami. Even the fish can’t fight against the water’s will and are often displaced.

Swimmers, divers, surfers, and boaters should evacuate the waters as soon as the first information statement is issued. You’re not going to see strong currents, or at least not until it’s too late.

Dangerous Debris

You’ve beaten the wave, and you’re fighting the currents. It means nothing if debris strikes you in the head. 

Tsunamis can carry entire cars and homes with them. The last place you want to be is clinging to a tree and waiting it out.

Why are tsunamis so dangerous?

Water is the most dangerous part of a tsunami. The columns of ocean water rush towards land, steadily growing in strength and can come miles inland.

Impact waves and currents bring water that remains after the tsunami retreats back to the sea.

Can you survive tsunami?

We mention that sometimes people don’t get the warnings or are just so close to the affected area that they can’t retreat.

You can survive it, but do your best to avoid having to try.

Higher Ground 

You might not get much warning time, and you’ve got to think on your feet to decide the best course of action.

You want to try and get about 2 miles away from the coast and find a place 100 feet above sea level.

How strong is tsunami?

Crest to crest, a tsunami can measure hundreds of miles in length. What’s scarier is that the deepest part of a tsunami can move over 500mph.

That’s as fast as a jet plane.

As the ocean floor gets shallower, a tsunami slows down to about 20 to 30mph. But that’s still too fast to try to outrun, much less outswim.

Disaster Kit

It can not be stressed enough that there is nothing wrong with disaster preparation. Expecting the unexpected not only sometimes means saving yourself, but it means saving other humans.

Why are tsunamis scary?

The scariest part of tsunamis is the lack of control we have. One has the power to kill hundreds of houses of people almost instantly, leave atomic bomb-level destruction, and can submerge entire buildings.

Take Shelter

Inland and upward are not always possible in the event of a tsunami. Sometimes, all you can do is find a secure shelter.

Many coast land towns and villages have private or community tsunami shelters.

A Stump May Save a Life

Debris is dangerous, but it can also save a life. The waves and currents drag you under, and you need a way to fight against them. Grabbing onto a stump or floating debris will work as a floating device. 

Understanding the Risk

As with any natural or weather event, knowing the tsunami risk level in your region is a must. You can better prepare by doing quick drills and packing a well-stocked emergency kit.

What is the most dangerous part of a tsunami? 

  1. Tsunamis cause dangerous flooding.
  2. Wave impact destroys everything in its path.
  3. Causes instant erosion.
  4. The currents carry it all.
  5. A tsunami creates waves of large and dangerous debris.

By AlwaysReadyHQ Team

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Location: Atlanta, GA, USA

The AlwaysReadyHQ Team is made up of writers and editors with experience ranging from emergency paramedics to former FEMA policy writers to natural disaster reporters.

Our goal is to provide clear, concise, organized, realistic, and actionable information to help you and your family feel comfortable and ready for anything. Less scared and more prepared.

We only source from authoritative sources such as government agencies and industry associations to bring reliable information to directly to you.

Andrew Riley - Contributing Editor

Andrew grew up in a country known for earthquakes, volcanoes, and typhoons. But despite the chaos and destruction of natural disasters, he remembers the resilience and readiness of neighbors, despite a lack of official government aid. He hopes that his team of experienced writers bring a bit of that to all of AlwaysReadyHQ's readers.